<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-12-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001274644</issuerCik>
        <issuerName>Ocera Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>OCRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001580787</rptOwnerCik>
            <rptOwnerName>Shah Pratik</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OCERA THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>525 UNIVERSITY AVENUE, SUITE 610</rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94301</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.85</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-08-30</value>
                <footnoteId id="F2"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-08-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Option to purchase Common Stock granted by the Issuer pursuant to the Issuer's Second Amended and Restated 2011 Stock Option and Incentive Plan (the &quot;Plan&quot;), qualified under Rule 16b-3(d).</footnote>
        <footnote id="F2">The Issuer granted the option on August 30, 2013, subject to stockholder approval of the Plan, which was obtained on December 19, 2013.</footnote>
        <footnote id="F3">The option shall vest and become exercisable with respect to 25% of the shares covered by the grant on August 30, 2014, subject to the Reporting Person's continued service to the Issuer through such date, with the balance to vest in equal monthly installments over the next succeeding three year period, subject to the Reporting Person's continued service to the Issuer through each such date.</footnote>
    </footnotes>

    <remarks>Exhibit 24.1 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Jeryl L. Hilleman, Attorney-In-Fact</signatureName>
        <signatureDate>2013-12-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
